1. Field of the Invention
The present invention relates generally to the field of trailer covers, and more specifically, to a trailer tarp cover system that uses a main arm with a rectangular joint at its base to open and close the cover.
2. Description of the Related Art
The present invention is a side-to-side tarp cover system for a grain trailer of the type shown in FIG. 1. There exist a number of side-to-side tarp cover systems for grain trailers, some of which are manually operated and others of which are electronically operated. Among the electronically operated tarp cover systems are those depicted in U.S. Pat. Nos. 6,199,935, 6,206,449 and 6,513,856, discussed below. An example of a manually operated side-to-side tarp system is described in U.S. Pat. No. 7,513,561, also discussed below. None of these systems utilizes a rectangular joint at the base of the main arm, as in the present invention. The rectangular joint of the present invention provides mechanical advantages not present in the inventions discussed below.
U.S. Pat. No. 6,199,935 (Waltz et al., 2001) discloses a flexible sheet cover apparatus for a load-carrying box on a land vehicle in which an arm is coupled to a roller for rolling and unrolling the flexible sheet from side to side. The arm is in the form of a box beam with a fixed length, and the arm has a slot. A pin is coupled to the load-carrying box and slidably engaged in the slot in the arm to define a pivot for the arm. The roller remains in constant contact with the top edges of the two non-contiguous walls that form the load-carrying box. A motor is fixed to the arm between the roller and the slot, and a drive unit enclosed within the box beam couples the motor to the roller.
U.S. Pat. No. 6,206,449 (Searfoss, 2001) provides an apparatus for extending and retracting a cover over a bed of a truck. The main arm, which is located at the rear of the truck bed, has a first base and a first extension. The bearing arm, which is located at the front of the truck bed, has a second base and a second extension. The first extension is pivotally connected to the upper end of the first base, and the second extension is pivotally connected to the upper end of the second base. A reel extends between distal ends of the first and second extensions. A motor is mounted on the distal end of either the first or second extension and is also connected to the distal end of the reel.
U.S. Pat. No. 6,513,856 (Swanson et al., 2003) involves a mechanism for rolling and unrolling a tarp over a trailer container. An electrically operated drive assembly is used to roll the roll bar back and forth between longitudinal edges of the container. The drive assembly comprises an electric motor and a gear reduction mechanism, both of which are supported on a telescoping tube assembly that is pivotably attached to the front of the container. A double reel member is fixedly attached to the forward end of the roll bar, and a single reel member is fixedly attached to the rearward end of the roll bar. Constant force spring members are fixedly attached to the double and single reel members and also to hinge plates mounted on the side of the container.
U.S. Pat. No. 7,513,561 (Royer, 2009) discloses a device for covering and uncovering the top of a container with a tarp, the device comprising a rod, a rod rotating component, and an actuator. The tarp is rolled around the rod when the cover is in a retracted position, and the rod rotating component is couple to the rod such that rotating the rod rotating component around its longitudinal axis also rotates the rod around its longitudinal axis. The rod rotating component is linked to an actuator that is operated manually and that causes the rod rotating component to rotate about its longitudinal axis. The length of the rod rotating component varies to allow the rod to remain linked to the actuator as the rod travels over the top of the container.
Examples of tarp covering systems that involve front-to-back rather than side-to-side retraction and extension systems include: U.S. Pat. No. 7,111,891 (O'Brian et al., 2006); U.S. Pat. No. 6,893,071 (Chabot, 2005); U.S. Pat. No. 6,318,790 (Henning, 2001); U.S. Pat. No. 6,942,274 (Henning, 2005); and U.S. Pat. No. 6,575,519 (Henning, 2003).